1. Field of the Invention
The present invention relates to a method and system for monitoring the behavior of a tyre during the running of a motor vehicle equipped with tyres. The present invention relates also to a method for controlling a vehicle.
2. Description of the Related Art
Tyre monitoring systems using accelerometers disposed within tyres have already been proposed.
EP patent application no. 887,211 describes a tyre monitoring system for a tyre on a vehicle comprising: a sensor device operatively arranged with respect to the tyre to create an electrical pulse during the footprint pass corresponding to a deformation of the tyre; means for calculating a ratio of the duration of said electrical pulse to the duration of one tyre revolution; means for transmitting said ratio to an evaluating unit placed in the vehicle. The sensor device is placed within the tread area of said tyre in order that said electrical pulse presents a first maximum at the entrance and a second maximum at the leaving of said footprint pass. The sensor device can be an accelerometer that measures the intensity of the acceleration supported by the tread. The aim of the solution disclosed in the '211 patent application is the monitoring of the tyre deflection in order to obtain an optimum performance, particularly for truck tyres.
U.S. Pat. No. 6,204,758 describes a tyre monitor for use in a remote tyre monitor system including an accelerometer for detecting acceleration of the tyre monitor. Position information for the tyre monitor is determined in response to the acceleration. In this manner, tyre position information is determined automatically to allow the system to display tyre characteristic data such as air pressure in conjunction with tyre position. More particularly, the tyre monitor includes a housing and a valve stem and is configured for mounting on a wheel of a vehicle. The valve stem opens to admit air for filling the tyre and for manual checks of the tyre pressure. Otherwise, the valve stem generally remains closed to seal the tyre. The tyre monitor includes a radial accelerometer, a tangential accelerometer, a yaw accelerometer, and a pressure sensor.
PCT patent application no. 98/56606 discloses a method for monitoring a running motor vehicle tyre, and, in particular, a device comprising: a sensor mounted on the wheel, coupling means transmitting to the vehicle indications obtained from the sensor and power supply means. The sensor is a miniature sensor sensitive to acceleration, implanted in the tyre running tread or in proximity thereof. The coupling means, mounted on the wheel, transmit the indications relative to the measurements carried out when the running tread is in contact with the ground. More particularly, the authors consider a tyre having a radius R traveling at a speed V. A tyre portion BC, having a length L, is in contact with ground, under load. In a point A, outside the portion BC, the centrifugal radial acceleration is V2/R. On the other hand, between the points B and C the centrifugal radial acceleration is substantially zero, in that the differential speed of the tyre with respect to the ground is substantially zero. By implanting an accelerometer within the tyre, the portion BC can be detected. The aim disclosed by the authors for such kind of measurement is to detect a possible under-inflation of a tyre.